Front part of a motor vehicle having a fender unit

ABSTRACT

The invention relates to a front part of a motor vehicle having a fender unit which comprises a front fender which is covered on the outside by a fender covering, and which is connected in its lower region to a bottom supporting structure of the motor vehicle, an air guiding part being arranged underneath the fender. 
     According to the invention, in the event of a head-on impact the air guiding part interacts with the fender covering and stiffens it in a region which is positioned in front of the fender, the air guiding part being supported on the bottom supporting structure.

BACKGROUND AND SUMMARY OF THE INVENTION

This application claims the priority of International application No.PCT/EP01/08454 filed Jul. 21, 2001, and German Patent Document No. 10112 424.4 filed Mar. 15, 2001, the disclosures of which are expresslyincorporated by reference herein.

The invention relates to a front part of a motor vehicle having a fenderunit.

German Patent Document No. DE 38 25 071 C1 has already disclosed a frontpart of a motor vehicle with a fender unit which is connected to abottom supporting structure of the motor vehicle and in which coolingair openings are made in a fender covering in order to supply coolingair to the drive assemblies arranged behind the fender unit. The coolingair openings are arranged above and below a transverse carrier which isassociated with the fender unit and into which a fender which is elasticwith respect to impacts is integrated.

In order to pass on the air flowing through the cooling air openings tothe drive assemblies with as few flow losses as possible, an air guidingpart, which forms an air guiding duct, is arranged between the fendercovering and the bottom supporting structure.

With such or similar additional assemblies for improving the efficiencyof the drive assemblies in the front region of a motor vehicle, thepacking density is increased more and more so that there is lessstructural free space for the configuration of measures to improvepedestrian protection in the event of collisions.

The invention is therefore based on the object of developing a frontpart of a motor vehicle of the generic type to the effect that, whilemaintaining the advantageous effect of the air guiding part, protectionof pedestrians in the event of a collision is improved.

By reinforcing the fender covering with a component which is alreadypresent, such as the air guiding part, the structural space which isavailable in the front of the motor vehicle for improving the impactprotection for pedestrians is utilized to an optimum degree. Here, theair guiding part has a reinforcing effect on the fender covering in aregion positioned in front of the fender so that in the event of acollision a pedestrian firstly enters into contact with this regionwhich runs approximately at the level of the pedestrian's lower legs.The movement impetus which acts in the lower leg region away from thefront part of the motor vehicle causes the pedestrian to be slung aroundabout the center of gravity of his body so that his upper body moves inthe direction of the engine hood. In the process, the fender which is ofresilient construction is pressed in so that the pedestrian rolls acrossthe engine hood in a defined fashion. At the same time, thereinforcement of the fender covering acts as an under-ride protectionfor pedestrians so that they cannot be pulled under the motor vehicle inthe event of a collision. The air guiding part is set here in such a waythat the necessary supporting force is reached quickly and maintainedwhile the acceleration values and the necessary penetration paths forthe pedestrian are preserved.

As the air guiding part extends over virtually the entire width of amotor vehicle, the fender covering is also reinforced in the lateralregions of the front part of the motor vehicle, and at the same time thecross-sectional surface which is available in the front area of themotor vehicle is used to an optimum degree for feeding cooling air.

In one preferred embodiment, the air guiding part is supported at thefront end by two longitudinal carrier sections which are associated withthe bottom supporting structure. The air guiding part is embodied as aninjection-molded part, and the plastic used should be relatively rigid,impact-resistant and not too brittle. The connection to the front endsof the longitudinal carrier sections permits stable support on alreadyexisting components which can be integrated into the injection-moldedpart without much additional expenditure on change.

A rear end collision protection element which is fitted over the frontends of the longitudinal carrier sections acts, in addition to itsfunction as a support of the air guiding part, as a rear end collisionprotection in the event of minor damage. For example, when the rear endof the motor vehicle strikes against curves or the like, thelongitudinal carrier sections which are associated with the supportingstructure can be protected to an optimum degree against damage by therear end collision protection element. The rear end collision protectionelement is preferably manufactured from plastic so that adaptation tovirtually any shape of the connection between the supporting structureand the air guiding part can be brought about.

In order to reduce the manufacturing costs further, the air guiding partcan be constructed as one piece with the rear end collision protectionelement.

As a result of the air guiding part extending laterally beyond thesupporting points on the front ends of the longitudinal carriersections, the pedestrian protection is also provided even when there isan offset collision with a pedestrian.

In order to support the air guiding part uniformly on the fendercovering, the contour of the air guiding part which faces the fendercovering is adapted to the internal contour of the fender covering. Inaddition, the fender covering can be prestressed by the air guiding partin order to improve the dimensional stability of the fender covering.

In one particularly preferred embodiment, the air guiding part has awing-like shape. In order to make the air guiding part inherentlystable, a number of reinforcement ribs which are oriented in thelongitudinal direction of the motor vehicle and which are spaced apartfrom one another in the transverse direction of the motor vehicle arearranged on the upper side of the wing.

Reinforcement ribs which extend from the underside of the wing in thedirection of the fender covering act in a particularly reinforcingfashion in the lower region of the fender covering. The matching of theterminating edge of each reinforcement rib to the internal contour ofthe fender covering particularly increases the degree of rigidity inthis region so that in the event of a crash the lower limb of apedestrian can bounce off.

The formation of an at least partially closed hollow section by thecovering, the fender, and the air guiding part provides furtherreinforcement in order to protect pedestrians against impacts withsimple means. Here, the wing can be attached by its terminating edges tothe fender covering, or else only bear against it.

In addition to supporting the air guiding part on both sides on thefront ends of the longitudinal carrier sections it is possible toprovide support on a transverse carrier which connects the frontlongitudinal carrier sections. This further improves the degree ofrigidity of the fender covering in the lower region.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantageous refinements of the invention are explained belowwith reference to the drawings, in which:

FIG. 1 shows a longitudinal sectional view at the level of a right-handlongitudinal carrier of a front part of a motor vehicle as taken alongline I—I in FIG. 3,

FIG. 2 shows a longitudinal sectional view at the level of the motorvehicle center of the front part of a motor vehicle as taken alone lineII—II in FIG. 3,

FIG. 3 shows a plan view of the air guiding part which is illustrated inFIGS. 1 and 2,

FIG. 4 shows a longitudinal sectional view at the level of the motorvehicle center of a front part of a motor vehicle in a second embodimentas taken along line II—II in FIG. 3,

FIG. 5 shows a perspective oblique view of an air guiding part in athird embodiment, and

FIG. 6 shows a perspective view of the arrangement of the air guidingpart according to FIG. 5 in the fender unit in a perspective obliqueview from behind.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a front part 1 of a motor vehicle having a fenderunit 2 in a longitudinal section which runs at the level of a frontlongitudinal carrier section 3, the longitudinal carrier section 3 beingassociated with a bottom supporting structure (not illustrated in moredetail) of a motor vehicle.

The fender unit 2 comprises a front fender 4 and a fender covering 5.

The front fender 4 is formed by a transverse carrier 6 which isconnected to a supporting component 8 of the motor vehicle by an impactabsorber 7. An impact foamed part 10, which extends over virtually theentire width of the motor vehicle, is attached to the front end side 9of the transverse carrier 6 which is embodied as a two-chamber hollowsection. The impact foamed part 10 has a U-shaped cross section.

The front part 1 of the motor vehicle is terminated at the front by thefender covering 5 which is connected in the upper region to a motorvehicle bodywork frame part 11 and a side part 12 by a screwedconnection 13. A cooling air opening 14 which extends at least partiallyover the width of the motor vehicle is made in the fender covering 5below the front fender 4 in order to supply sufficient cooling air tothe drive assemblies arranged in the engine cavity 15. In this exemplaryembodiment, the cooling air opening 14 is configured to supply coolingair to a charge air cooler which is, however, not illustrated in FIG. 1.

An air guiding part 16 which is attached by a rear end collisionprotection element 17 to the front end 18 of the longitudinal carriersection 3 is arranged underneath the cooling air opening 14. For thispurpose, the rear end collision protection element 17 is constructed asa single plastic component together with the air guiding part 16, therear end collision protection element 17 being attached in its rearregion 19 to the longitudinal carrier section 3 by a screwed connection20. The rear end collision protection element 17 is shaped in such a waythat its internal contour is essentially matched to the external contourof the front end 18 of the longitudinal carrier section so that the rearend collision protection element 17 can easily be fitted over the frontend 18. At the same time, the lower lip 21, extending underneath thecooling air opening 14, of the fender covering 5 is attached by ascrewed connection 22 to the rear end collision protection element 17and thus to the front longitudinal carrier section 3.

The air guiding part 16 extends in a wing shape over virtually theentire width of the motor vehicle, irrespective of whether or not acooling air opening 14 is arranged above. With its terminating edge 23which faces the fender covering 5, the air guiding part 16 which extendsin a tongue shape in the longitudinal direction of the motor vehiclebears against the inner contour 24 of the fender covering 5, the innercontour 24 being formed in the abutment area of the terminating edge 23as an engagement angle 25 in order to support the air guiding part 16 ina way which is low in vibration. In order to reinforce the air guidingpart 16, reinforcement ribs 26 which are oriented in the longitudinaldirection of the motor vehicle are arranged on the upper side of the airguiding part 16. Depending on the desired degree of rigidity, the numberof reinforcement ribs 26 can be increased in the transverse direction ofthe motor vehicle, the distances between the reinforcement ribs 26 beingcorrespondingly reduced.

Covering the lower lip 21 with the air guiding part 16 results in an airguiding duct 27 which is closed at least in the downward direction andthrough which the air which flows in is directed to the charge aircooler in a selected fashion. The tongue-shaped configuration of the airguiding part makes it possible to ensure that the air which has flowedin is used to an optimum degree without undesired flow losses occurring.At the same time, adaptation to the structural conditions in the frontarea of the vehicle occurs, the air stream which enters through thecooling air opening 14 being capable of being oriented in a selectedfashion with respect to the drive assembly which is to be cooled.

When there is a pedestrian collision, the air guiding part 16 acts in areinforcing fashion on the lower lip 21 which is associated with thefender covering 5 and is positioned slightly in front of the fender 4.The lower lip 21 is correspondingly the component in the front part 1 ofthe motor vehicle which protrudes furthest forward. The consequence ofthis is that when there is a collision with a pedestrian, firstly itslower limb is sensed by the lower lip 21 by the region A marked with acircle in FIG. 1. The reinforcement of the lower lip 21 with the airguiding part 16 in precisely this region A moves the pedestrian's legsaway from the motor vehicle in the direction of travel F so that thepedestrian is deflected about the center of gravity. When there is animpact against the impact foamed part 10, impact forces are absorbed bythe pressing in of the impact foam while the pedestrian rolls over theengine hood in a defined fashion. This virtually rules out thepossibility of the pedestrian with which there has been a collisionbeing run over. For this purpose, the engine hood can be equipped withfurther measures for protecting pedestrians, for example, an airbag inthe region of the upper edge of the engine hood. In further embodiments,the lower lip 21 can be embodied so as to be flush with the contour ofthe fender covering or positioned slightly behind it.

FIG. 2 illustrates a longitudinal section through the center of thefront part 1 of the motor vehicle, identical reference symbolscharacterizing identical components.

The assemblies which are to be cooled are also apparent from FIG. 2, 28designating a radiator, 29 designating a fan and 30 designating thecharge air cooler which has already been mentioned in FIG. 1. Incontrast to FIG. 1, a transverse carrier 31 of the bottom supportingstructure can be seen here, the transverse carrier 31 connecting thefront longitudinal carrier sections 3 (not illustrated here) to oneanother.

Above the transverse carrier 6 which is connected to the impact foamedpart 10, a further cooling air opening 32, which is covered with aradiator grill 33, is provided in the fender covering 5. The air whichflows in through the radiator grill 33 is fed to the radiator 28 locatedbehind it. Above the radiator grill 33 there is an adjoining engine hood34.

The air guiding part 16 is formed in the shape of a tongue in the centerof the motor vehicle and thus conducts the air flowing in through thecooling air opening 14 directly to the charge air radiator 30. Thetongue-shaped cross section promotes reduction in the air in thedirection of the charge air cooler 30 without unnecessary leak lossesarising due to eddying.

In order to provide support in the center of the motor vehicle on thebottom supporting structure, the air guiding part 16 is connected to thetransverse carrier 31. For this purpose, the end 35 which faces thetransverse carrier 31 is embodied in a fork shape. The end 35 which isformed as a fork 36 is partially fitted over the transverse carrier 31and attached to it by a screwed connection 37.

The air guiding part 16 in turn extends from the fork 36 as far as theinner contour 25 of the lower lip 21 which is associated with the fendercovering 5 and acts in a reinforcing fashion on the fender covering 5when there is a collision with a pedestrian in the region A. The airguiding part 16 has, analogously to FIG. 1, reinforcement ribs 26 on itsupper side. In order to improve the degree of rigidity, reinforcementribs 38 are additionally provided on the underside of the air guidingpart 16.

FIG. 3 illustrates a schematic plan view of the air guiding part 16 fromabove, the air guiding part 16 extending in a wing shape over virtuallythe entire width of the motor vehicle and beyond the supports 39 and 40(described in FIG. 1) on the front longitudinal carrier section 3.

Longitudinal section illustrations which have already been described inFIGS. 1 and 2 are shown with lines I—I for FIG. 1, and II—II for FIG. 2.

As shown FIG. 3, the reinforcement ribs 26 are distributed over theentire extent of the air guiding part 16 in the transverse direction ofthe motor vehicle.

An additional support 41 (illustrated by dot dash lines) is optionallyarranged on the transverse carrier 31 between the supports 39 and 40provided on the longitudinal carrier sections 3, the supports havingalready been described by an exemplary embodiment in FIG. 3. Of course,further additional supports 41 may also be provided in order to preventpossibly occurring natural oscillations of the air guiding part 16.

A further exemplary embodiment of the support 41 on the transversecarrier 31 is illustrated in FIG. 4 along the line II—II from FIG. 3.

The front part 1 of the motor vehicle is constructed analogously to theexemplary embodiment illustrated in FIG. 2 and differs only in the formof the air guiding part 16.

The air guiding part 16 then extends from the cooling air opening 14over the lower lip 21 as far as the transverse carrier 31 of the bottomsupporting structure. In the region of the cooling air opening 14, theair guiding part 16 is embodied as a cooling air grill 42 and isattached to opening edges 44 of the cooling air opening 14 by latchingprojections 43. The air guiding part 16 is of step-shaped constructionunderneath the cooling air opening 14 in order to direct the air whichflows in through the cooling air opening 14 in a selected fashion to thecharge air radiator 30. In contrast to the first exemplary embodiment inFIG. 2, the terminating edge 23 is welded to the lower opening edge 44of the cooling air opening 14. Alternatively, another means ofattachment, for example clipping, may also be provided. The air guidingpart 16 bears with a part region 46 against the lower termination 45 ofthe lower lip 21 and is also fastened there by welding or clipping.

The support 41 on the transverse carrier 31 is provided by a screwedconnection 47. Alternatively, in the region of the support on thetransverse carrier 31, the air guiding part 16 may be of similarconstruction to the fork 36 in FIG. 2.

As in the exemplary embodiment in FIG. 2, the air guiding part 16 hasreinforcement ribs 26 and 38 both on its upper side and on its lowerside. However, in contrast to FIG. 2, the reinforcement ribs 26 and 38are configured with a significantly large area in order to reinforce thelower lip 21 further in the lower region of the fender covering 5. Inparticular, the contour 48 of the reinforcement rib 38 is approximatedto the inner contour 49 of the lower lip 21 so that the cavity 50 whichis formed by the lower lip 21 and the air guiding part 16 is closedvirtually entirely by the reinforcement rib 38. When there is acollision with a pedestrian, there is a strong impact effect as a resultof the reinforced lower lip 21 against the pedestrian's lower leg, andthe pedestrian is thus pushed away from the motor vehicle with the partof his body lying below the center of gravity of his body, and is movedwith the upper part of his body onto the engine hood. At the same time,this promotes the leg region of the pedestrian being moved out of thedanger area of the front wheels.

FIG. 5 illustrates a third exemplary embodiment of an air guiding part16 which is suitable for an elongated front part 1 of a motor vehiclewhose front longitudinal carrier sections 3 are arranged above theregion A which is critical for the impact with a pedestrian.

In order to support the air guiding part 16 on the longitudinal carriersections 3 which are formed as a closed box profile, struts 51 areprovided which are attached to the underside of each longitudinalcarrier section 3, for example, with a welded connection. The struts 51are oriented here, in terms of the vertical axis of the motor vehicle,with their lower end obliquely forward, the orientation of the struts 51being however dependent on the arrangement of the fender system withrespect to their position in relation to the supporting structure 3.

The lower ends of the struts 51 are connected to one another over thewidth of the motor vehicle by a carrier part 52 which has a higherdegree of rigidity than the air guiding part 16 which is composed, forexample, of plastic. The higher degree of rigidity of the carrier partmay be achieved, for example, by constructing the carrier part as aclosed box profile made of sheet metal. Given a correspondingconfiguration of the air guiding part 16, the force which acts whenthere is an impact with a pedestrian can be absorbed sufficientlyquickly by the air guiding part 16 and passed onto the bottom supportingstructure via the carrier part 52 and the struts 51. The air guidingpart 16 is set here in such a way that the necessary supporting force isreached quickly and maintained while values the acceleration andnecessary penetration paths for the pedestrian are preserved.

FIG. 6 shows the positioning of the air guiding part 16 with respect tothe fender covering 5 and the impact foamed part 10. The cooling airopening 14 which is partially covered with webs 53 is bounded in itslower region, analogously to the exemplary embodiments described aboveaccording to FIGS. 1 to 4, by the lower lip 21 of the fender unit 2. Incontrast to conventional fender units, the front termination of theimpact foamed part 10 bears with the critical region A of the lower lip21 in a virtually vertically extending transverse plane of the motorvehicle. In this way, the lower leg region of a pedestrian receivesimpetus over a large area counter to the direction of travel when thereis an impact so that the upper body can roll in a defined fashion in thedirection of the engine hood.

The formation of the air guiding part is illustrated here by way ofexample with reinforcement ribs 54 which are arranged on the undersideof the air guiding part 16 over the width of the motor vehicle. As aresult, a controlled degree of rigidity is obtained over the entirewidth of the motor vehicle, preventing the lower leg region penetratingor rotating too far into the lower lip 21. The air guiding part 16 canbe supported on the inner contour 24 of the lower lip 21 by appropriateconnecting technology such as screws, bonding, or rivets, in order toachieve effective force support.

The degree of rigidity of the air guiding part 16 can be individuallymatched by the following factors to the necessary force/displacementcharacteristic which is specific to the motor vehicle and fender:

-   -   type of material, material thickness and material geometry;    -   position, size, embodiment and wall thickness of the        reinforcement ribs;    -   alternative use of net-shaped or honeycomb-shaped reinforcement        structures;    -   the degree of rigidity of the carrier part 52 is preferably        higher than that of the air guiding part 16 (alternatively, the        carrier part 52 can be matched to the air guiding part 16 in        such a way that joint deformation of both parts is possible);    -   connecting technologies between the lower lip 21 and a guiding        part 16; and    -   position and design of the reinforcement ribs 54 over the width        of the motor vehicle.

Irrespective of the aforesaid factor for matching the force/displacementcharacteristic, the air guiding part 16 is constructed in such a waythat an approximately identical deformation behavior, and thus identicalkinematics of the impact of the leg, can be ensured over the entirewidth of the motor vehicle.

1. A front part of a motor vehicle having a bumper unit which comprisesan air guiding part which is disposed under a cooling air openingdefined by a fender covering and which is connected in a lower region toa bottom supporting structure of the motor vehicle and wherein a regionof connection between the fender covering and the air guiding partextends beyond a portion of the fender covering that is disposed abovethe cooling air opening, wherein in an event of a head-on impact, theair guiding part interacts with the fender covering and stiffens thefender covering in a region which is positioned in front of a frontfender.
 2. The front part of a motor vehicle as claimed in claim 1,wherein the air guiding part extends over an entire width of the motorvehicle.
 3. The front part of a motor vehicle as claimed in claim 1,wherein the air guiding part is supported by a front end of twolongitudinal carrier sections which are associated with the bottomsupporting structure.
 4. The front part of a motor vehicle as claimed inclaim 3, wherein a rear end collision protection element is connected tothe air guiding part and is fitted over each of the front ends of thelongitudinal carrier sections.
 5. The front part of a motor vehicle asclaimed in claim 4, wherein the air guiding part is constructed as onepiece with the rear end collision protection element as a plastic part.6. The front part of a motor vehicle as claimed in claim 3, wherein theair guiding part extends laterally beyond supports disposed on thelongitudinal carrier sections.
 7. The front part of a motor vehicle asclaimed in claim 1, wherein a contour of the air guiding part whichfaces the fender covering is adapted to an internal contour of thefender covering and wherein the contour of the air guiding part bearsagainst and is connected to the internal contour of the fender covering.8. The front part of a motor vehicle as claimed in claim 1, wherein theair guiding part is embodied in one piece with the fender covering. 9.The front part of a motor vehicle as claimed in claim 1, wherein the airguiding part has a wing-like shape and a plurality of reinforcement ribswhich are oriented in a longitudinal direction of the motor vehicle, arespaced apart from one another in a transverse direction of the motorvehicle, and are arranged on an upper side of the wing-like shape. 10.The front part of a motor vehicle as claimed in claim 9, wherein atleast one of the plurality of reinforcement ribs is arranged on anunderside of the wing-like shape, the contour of the at least onereinforcement rib which lies opposite the fender covering being matchedto an internal contour of the fender covering.
 11. The front part of amotor vehicle as claimed in claim 9, wherein the air guiding part formsa closed hollow section together with a region of the fender coveringwhich is positioned in front of the air guiding part.
 12. The front partof a motor vehicle as claimed in claim 3, wherein a support is providedon a transverse carrier and wherein the transverse carrier connects thetwo longitudinal carrier sections.
 13. A front part of a motor vehicle,comprising: a fender; a cover disposed over the fender and defining acooling air opening; and an air guiding part, wherein the air guidingpart is disposed under the cooling air opening and is connected to thecover at a front end and to a bottom supporting structure of the motorvehicle at a rear end and wherein a region of connection between thecover and the air guiding part extends beyond a portion of the coverthat is disposed above the cooling air opening.
 14. The front part of amotor vehicle as claimed in claim 13, wherein a contour of the airguiding part matches a contour of the cover.
 15. The front part of amotor vehicle as claimed in claim 13, wherein the air guiding partextends over a width of the motor vehicle.
 16. The front part of a motorvehicle as claimed in claim 13, wherein the air guiding part issupported by a front end of two longitudinal carrier sections which areassociated with the bottom supporting structure.
 17. The front part of amotor vehicle as claimed in claim 16, wherein a rear end collisionprotection element is connected to the air guiding part and is fittedover each of the front ends of the longitudinal carrier sections. 18.The front part of a motor vehicle as claimed in claim 17, wherein theair guiding part is constructed as one piece with the rear end collisionprotection element as a plastic part.
 19. The front part of a motorvehicle as claimed in claim 16, wherein the air guiding part extendslaterally beyond supports disposed on the longitudinal carrier sections.20. The front part of a motor vehicle as claimed in claim 13, whereinthe air guiding part has a wing-like shape and a plurality ofreinforcement ribs which are oriented in a longitudinal direction of themotor vehicle, are spaced apart from one another in a transversedirection of the motor vehicle, and are arranged on an upper side of thewing-like shape.
 21. The front part of a motor vehicle as claimed inclaim 20, wherein at least one of the plurality of reinforcement ribs isarranged on an underside of the wing-like shape, the contour of the atleast one reinforcement rib which lies opposite the cover being matchedto an internal contour of the cover.
 22. The front part of a motorvehicle as claimed in claim 20, wherein the air guiding part forms aclosed hollow section together with a region of the cover which ispositioned in front of the air guiding part.
 23. The front part of amotor vehicle as claimed in claim 16, wherein a support is provided on atransverse carrier and wherein the transverse carrier connects the twolongitudinal carrier sections.
 24. A front part of a motor vehiclehaving a bumper unit which comprises an air guiding part which isarranged underneath a fender covering and a front fender and which isconnected in a lower region to a bottom supporting structure of themotor vehicle, wherein the air guiding part is supported by a front endof two longitudinal carrier sections which are associated with thebottom supporting structure, and wherein in an event of a head-onimpact, the air guiding part interacts with the fender covering andstiffens the fender covering in a region which is positioned in front ofthe front fender.
 25. The front part of a motor vehicle as claimed inclaim 24, wherein a rear end collision protection element is connectedto the air guiding part and is fitted over each of the front ends of thelongitudinal carrier sections.
 26. The front part of a motor vehicle asclaimed in claim 25, wherein the air guiding part is constructed as onepiece with the rear end collision protection element as a plastic part.27. The front part of a motor vehicle as claimed in claim 24, whereinthe air guiding part extends laterally beyond supports disposed on thelongitudinal carrier sections.
 28. The front part of a motor vehicle asclaimed in claim 24, wherein a support is provided on a transversecarrier and wherein the transverse carrier connects the two longitudinalcarrier sections.
 29. A front part of a motor vehicle having a bumperunit which comprises an air guiding part which is arranged underneath afender covering and a front fender and which is connected in a lowerregion to a bottom supporting structure of the motor vehicle, whereinthe air guiding part has a wing-like shape and a plurality ofreinforcement ribs which are oriented in a longitudinal direction of themotor vehicle, are spaced apart from one another in a transversedirection of the motor vehicle, and are arranged on an upper side of thewing-like shape, and wherein in an event of a head-on impact, the airguiding part interacts with the fender covering and stiffens the fendercovering in a region which is positioned in front of the front fender.30. The front part of a motor vehicle as claimed in claim 29, wherein atleast one of the plurality of reinforcement ribs is arranged on anunderside of the wing-like shape, the contour of the at least onereinforcement rib which lies opposite the fender covering being matchedto an internal contour of the fender covering.
 31. The front part of amotor vehicle as claimed in claim 29, wherein the air guiding part formsa closed hollow section together with a region of the fender coveringwhich is positioned in front of the air guiding part.
 32. A front partof a motor vehicle having a bumper unit which comprises an air guidingpart which is arranged underneath a fender covering and a front fenderand which is connected in a lower region to a bottom supportingstructure of the motor vehicle, wherein the air guiding part is arrangedunderneath a cooling air opening defined by the fender covering andwherein the air guiding part extends over an entire width of the motorvehicle, and further wherein in an event of a head-on impact, the airguiding part interacts with the fender covering and stiffens the fendercovering in a region which is positioned in front of the front fender.33. A front part of a motor vehicle having a bumper unit which comprisesan air guiding part which is arranged underneath a fender covering and afront fender and which is connected in a lower region to a bottomsupporting structure of the motor vehicle, wherein the air guiding partis embodied in one piece with the fender covering, and wherein in anevent of a head-on impact, the air guiding part interacts with thefender covering and stiffens the fender covering in a region which ispositioned in front of the front fender.